1. Field of the Invention
The present invention is related to TV audio standards, and more particularly to an audio multi-standard detection apparatus and method applied to analog TV broadcasting.
2. Description of Related Art
Among TV broadcasting signals, the audio signal portion is defined by TV Audio Standard, which includes standards of non-stereo broadcasting, stereo broadcasting, and bilingual broadcasting. Currently, the global TV Audio Standards can primarily be divided into four categories of audio broadcasting format: A2, EIAJ, BTSC, and NICAM, wherein A2 can be further divided into five standards of FM A2 BG, FM A2 DK1, FM A2 DK2, FM A2 DK3, and FM A2 M, while NICAM can be further divided into four standards: AM mono L NICAM, FM mono I NICAM, FM mono BG NICAM, and FM mono DK NICAM. Generally, in different countries or areas the broadcasting systems are different. For example, Japan has adopted the EIAJ broadcasting system as national standard; Taiwan and the United States use BTSC broadcasting system; Europe and China use the NICAM and A2 broadcasting systems, etc.
For currently known TV signal receiving apparatuses, dedicated circuit designs are usually employed for each audio broadcasting signal's format, so as to ensure that the carriers and decoding method will conform to their respective national standard. However, this approach actually limits the products in the sense that they can only function in limited countries or regions; if there is a need for the products in other regions, modifications in design are often necessary in order to match the broadcasting standard of that region. Consequently, not only the chip manufacturers have to design and manufacture different control chips for various TV audio standards, this also causes burden of development and design as well as difficulty of product maintenance on the TV manufacturers' part.